Molybdenum metal is used for various specialty applications which require its unusual properties. The melting point of molybdenum is 2630.degree. C., over 1000.degree. C. higher than iron, permitting its use in furnace parts, rocket nozzles and other high-temperature applications where most metals would melt or fail. Molybdenum has exceptionally good resistance to corrosion by mineral acids under non-oxidizing conditions.
However, because of its high melting point and poor ductility, molybdenum requires special manufacturing techniques.
A molybdenum part having acceptable mechanical properties typically depends on working the metal below its recrystallization temperature. When recrystallization is allowed to occur, the molybdenum has a tendency toward brittleness at lower temperatures (e.g., near room temperature and below). Recrystallization becomes particularly difficult to avoid if the manufacturing process requires brazing or welding, since recrystallization may easily occur at the brazing or welding site. Should recrystallization occur, the weld must subsequently be warm-worked to improve ductility. This tendency of recrystallized molybdenum to be brittle is one of the major deterrents to its use in many applications.